Google's Vic Gundotra leaves

GOOGLE'S top social networking executive is leaving the internet company after a near eight-year stint highlighted by an audacious challenge to Facebook.

Vic Gundotra on Thursday fittingly announced his departure in a post on Google Plus, a social network that debuted nearly three years ago. Gundotra had been in charge of Google Plus as the Mountain View, California, company's senior vice president of social.

Gundotra didn't explain his reasons for leaving nor did he reveal what he plans to do next.

"I am excited about what's next," Gundotra wrote.

"But this isn't the day to talk about that. This is a day to celebrate the past eight years. To cry. And smile. And to look forward to the journey yet to come."

"There are few people with the courage and ability to start something like that and I am very grateful for all (Gundotra's) hard work and passion."

Page didn't immediately announce a new leader for Google Plus.

Although it boasts more than 500 million users, Google Plus is still struggling to lure people into hanging out on its service for as long as they do on Facebook. And even with its rapid growth, Google Plus is still less than half the size of Facebook, which ended March with nearly 1.3 billion users and also boasts one of the most popular applications on smartphones and tablets.

Nevertheless, Google Plus has served its purpose by giving Google's search engine and other services more information about its users' identities and preferences. That information has helped Google sell more digital advertising, the main source of the company's revenue.

Before taking on the Plus project, Gundotra helped build some of the early apps for Google's Android operating system and led the drive to persuade outside programmers to create services tailored for Android.

Gundotra spent 15 years at Microsoft Corp before defecting to Google in 2006.